A new TBM that will excavate 18km of one of the twin tubes on the Lyon-Turin railway line has been unveiled at the Herrenknecht factory in Germany. The 10.4m diameter gripper TBM will excavate the central part of the Mont Cenis base tunnel between the Villarodin/Bourget-Modane access adit in France and the Clarea underground safety site in Italy.
This is the fourth of seven TBMs that will bore the twin bore Mont Cenis Base Tunnel project, and will be the first to cross the border between France and Italy.
Also present at the ceremony were the ELYOT group of companies, consisting of contractor Eiffage Génie civil (group head), Spie batignolles génie civil, Ghella and Cogéis, the project’s bi-national promoter TELT, and the Piedmont Region’s Transport Councillor, Marco Gabusi.
While the excavation is underway, shotcrete support will be applied to the tunnel walls, along with the bolts and ribs. Behind this, another 650m long machine called the Würm (worm) will be used to cast the final concrete lining.
The choice of this type of TBM has been dictated by several factors: the type of geology along the alignment, here consisting of relatively compact, uniform and stable formations; the great depth of the tunnels with more than 2,200m of overburden; and the associated geotechnical phenomena, such as detachments, ‘popping conditions’, or convergence. Not to mention the high temperatures present at these depths, highlighted by the exploration tunnel in La Maddalena in Chiomonte, which was used to establish the specifications for this new TBM.
CO5 is the construction site on the Mont Cenis base tunnel that crosses the border between Italy and France. It starts from the Villarodin-Bourget-Modane access adit, passes through the Ambin massif, and reaches the underground safety site of Clarea. At the same time as the 18km of tunnels that will be excavated by twin TBMs (36km in total), 7.8km of tunnels will also be dug using conventional methods. In total, around 15km of tunnels will be constructed using the conventional method, including the underground safety area at Modane.
Maurizio Bufalini, general director of TELT said, “This is the first of two TBMs that will cross the border, the most tangible symbol of our project: a railway that will unite Italy and France through the Alps, connecting our countries and Europe in a more efficient, economic and sustainable way. It is the fourth TBM that we have come here to receive in Schwanau and, as ever, it is always a great thrill. Its twin will be ready in February, and then it will be the turn of the two Italian TBMs. We will then have no less than seven of them digging to complete the 57.5 km tunnel, the longest railway tunnel in the world.”
Salah GHOZAYEL, CO5 project director said, “This operational construction site 5 is exceptional from various points of view: in terms of size, logistics, simultaneous excavation using both conventional and mechanised methods, along with the technical and human resources mobilised, all of which are constrained by the single access point provided by the Villarodin-Bourget/Modane access adit. All this means that the group of companies and all those involved will need to be truly adaptable.”
E.h. Martin Herrenknecht, CEO of Herrenknecht AG added, “The delivery of the Gripper TBM for the Mont Cenis Base Tunnel is yet another historical milestone for Herrenknecht. We are very proud to be part of such a lighthouse project that will bring Europeans across borders even closer together.”
Herrenknecht
Pioneering Underground Technologies - Herrenknecht AG is the technology and market leader in mechanized tunnelling. As the only company worldwide, Herrenknecht delivers cutting-edge tunnel boring machines for all ground conditions and in all diameters - ranging from 0.10 to 19 meters.
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